The answer is, you can't do it. **As an ordinary user you can't delete a page**. So the procedure is to remove all content from the page and replace it with {{Delete|reason}}. In this case you're removing the #RIDERECT #REDIRECT and replace that with {{Delete|created by mistake}}. You can expect a wiki admin to delete the page fully within a few weeks.
The [MediaWiki user help has a section on deleting a page][1] written by some very wise chap :-) As explained on that site, there are often better alternatives to deleting, but in this case the page should be deleted. It's clear-cut.
Note that the Delete label template is intended to be used in cases where the delete is clear-cut and should always *replace* all content of the page. In a case where you feel that a page should be deleted, but you're not confident enough to delete the content yourself (or disputed / potentially deputed deletes), you should use {{delete proposal}} instead ([Template:Delete proposal][2])
The reason a normal user is not allowed to delete a page, is the principle of [reversible change][3]. On a busy wikis which must also be vandal-proof, all user changes must be reversible *by other users*. In actual fact MediaWiki applies this principle to admin users too, so when an admin 'deletes' a page, this change can still be reversed by other admin users. So it turns out we never save any database space by deleting pages. The only benefit is de-cluttering search results.
[1]: http://www.mediawiki.org/wiki/Help:Deleting_a_page
[2]: http://wiki.openstreetmap.org/wiki/Template:Delete_proposal
[3]: http://meatballwiki.org/wiki/ReversibleChange
